Breast milk pumps are well-known, and generally comprise a hood that fits over the breast, a vacuum pump connected to the hood for generating an intermittent vacuum within the hood, and a receptacle for the expressed milk. Manually driven vacuum pumps as well as those that are driven by a motor are commonly used. The vacuum pumps of these devices, as a rule, intermittently generate a vacuum or negative pressure within the hood, with the hood encompassing the nipple and a substantial amount of the breast. The intermittent suction action of the pumps serves to pull on the breast and thereby extract milk in an action reminiscent of suckling. The milk so extracted typically flows from the hood into a collection container for storage and later use.
The disclosure of my U.S. Pat. No. 4,857,051 is hereby incorporated by reference. It discloses embodiments of breast pumps and methods of operating breast pumps suitable for use with the current invention. Milk expressed into a body hood or hood member under the operation of a manual or electric vacuum pump is collected in a container.
The disclosure of my U.S. Pat. No. 4,794,915 also is hereby incorporated by reference. It relates to a method for the stimulation of the nipples of the breasts of a pregnant woman in order, among other things, to enhance the production of labor-inducing hormones and to enable the performance of contraction stress-tests. This method often produces milk, sometimes in large volume. Therefore, it is also suitable for use with the current invention.
As noted in the above-incorporated U.S. Pat. No. 4,857,051, one significant failing of previous devices was that the milk expressed often reached the vacuum line or even the pump. In order to eliminate such a serious problem, many devices contain so-called safety volumes between the hood and the pump. Such a solution of the problem is expensive and usually cannot provide effective protection of the vacuum line and pump from milk. Also, varying degrees of the vacuum can be generated as the milk receptacle fills, which must then be compensated for.
In order to address these and other problems, U.S. Pat. No. 4,857,051 discloses a hood body or member to which a collecting or catch chamber is connected. At the outlet of the collecting chamber there is provided a valve which closes a passage leading from the collecting chamber to a receiving container. When a vacuum or negative pressure is applied to the hood from a suction device, the valve closes the collecting chamber outlet to the receiving chamber, but opens the outlet on the return cycle of the pump to force the milk expressed from the collecting chamber into the receiving chamber. A baffle arrangement is further described in conjunction with the valve mechanism in an attempt to prevent milk from passing into the vacuum line or from reaching the vacuum pump. In the disclosed embodiments, the baffle arrangement comprises a trap in which a separation wall 7 and a rear wall B form a vacuum passage 5 therebetween.
It has been discovered that a trap such as the type formed by the disclosed baffle arrangement may sometimes be less than completely effective in preventing milk from entering the vacuum line or reaching the pump. For example, it is possible for milk to be produced in such volume that it overflows the collecting or catch chamber 4 and overflows the trap, entering vacuum line 6. Such results may be encountered when using a stimulating technique such as disclosed in the above-incorporated U.S. Pat. No. 4,794,915. Accordingly, a more effective apparatus and method is needed to protect the vacuum pump and any associated hose or the like.